Larger columns and change of lysis buffer increase the yield of cell-free DNA extracted from amniotic fluid

Cell-free fetal nucleic acids (cffDNA) are present in maternal plasma and serum (1), but amniotic fluid (AF) also provides an attractive source of cffDNA. The concentration of cffDNA is 100- to 200-fold higher in AF than in maternal plasma/serum (2), but low yields of cffDNA compromise testing by techniques such as genomic microarrays, which require a minimum of 100 ng of DNA (3). For protocol optimization, we used 5 large-volume AF supernatant samples from patients who had undergone therapeutic amnioreduction for twin-twin transfusion syndrome. After optimization, we compared the DNA yield of the old and new protocols for freshly discarded AF supernatant samples from 29 euploid singleton pregnancies. Approval for this study was obtained from the Institutional Review Boards of Tufts-New England Medical Center and Women and Infant’s Hospital. The median gestational age at amniocentesis …